Refactor hyperparameter search backends (#24384)

* Refactor hyperparameter search backends

* Simpler refactoring without abstract base class

* black

* review comments:
specify name in class
use methods instead of callable class attributes
name constant better

* review comments: safer bool checking, log multiple available backends

* test ALL_HYPERPARAMETER_SEARCH_BACKENDS vs HPSearchBackend in unit test, not module. format with black.

* copyright

src/transformers/__init__.py

@@ -98,6 +98,7 @@ _import_structure = {
     "file_utils": [],
     "generation": ["GenerationConfig", "TextIteratorStreamer", "TextStreamer"],
     "hf_argparser": ["HfArgumentParser"],
+    "hyperparameter_search": [],
     "image_transforms": [],
     "integrations": [
         "is_clearml_available",

src/transformers/hyperparameter_search.py

+# coding=utf-8
+# Copyright 2023-present the HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from .integrations import (
+    is_optuna_available,
+    is_ray_available,
+    is_sigopt_available,
+    is_wandb_available,
+    run_hp_search_optuna,
+    run_hp_search_ray,
+    run_hp_search_sigopt,
+    run_hp_search_wandb,
+)
+from .trainer_utils import (
+    HPSearchBackend,
+    default_hp_space_optuna,
+    default_hp_space_ray,
+    default_hp_space_sigopt,
+    default_hp_space_wandb,
+)
+from .utils import logging
+
+
+logger = logging.get_logger(__name__)
+
+
+class HyperParamSearchBackendBase:
+    name: str
+    pip_package: str = None
+
+    def is_available(self):
+        raise NotImplementedError
+
+    def run(self, trainer, n_trials: int, direction: str, **kwargs):
+        raise NotImplementedError
+
+    def default_hp_space(self, trial):
+        raise NotImplementedError
+
+    def ensure_available(self):
+        if not self.is_available():
+            raise RuntimeError(
+                f"You picked the {self.name} backend, but it is not installed. Run {self.pip_install()}."
+            )
+
+    @classmethod
+    def pip_install(cls):
+        return f"`pip install {cls.pip_package or cls.name}`"
+
+
+class OptunaBackend(HyperParamSearchBackendBase):
+    name = "optuna"
+
+    def is_available(self):
+        return is_optuna_available()
+
+    def run(self, trainer, n_trials: int, direction: str, **kwargs):
+        return run_hp_search_optuna(trainer, n_trials, direction, **kwargs)
+
+    def default_hp_space(self, trial):
+        return default_hp_space_optuna(trial)
+
+
+class RayTuneBackend(HyperParamSearchBackendBase):
+    name = "ray"
+    pip_package = "'ray[tune]'"
+
+    def is_available(self):
+        return is_ray_available()
+
+    def run(self, trainer, n_trials: int, direction: str, **kwargs):
+        return run_hp_search_ray(trainer, n_trials, direction, **kwargs)
+
+    def default_hp_space(self, trial):
+        return default_hp_space_ray(trial)
+
+
+class SigOptBackend(HyperParamSearchBackendBase):
+    name = "sigopt"
+
+    def is_available(self):
+        return is_sigopt_available()
+
+    def run(self, trainer, n_trials: int, direction: str, **kwargs):
+        return run_hp_search_sigopt(trainer, n_trials, direction, **kwargs)
+
+    def default_hp_space(self, trial):
+        return default_hp_space_sigopt(trial)
+
+
+class WandbBackend(HyperParamSearchBackendBase):
+    name = "wandb"
+
+    def is_available(self):
+        return is_wandb_available()
+
+    def run(self, trainer, n_trials: int, direction: str, **kwargs):
+        return run_hp_search_wandb(trainer, n_trials, direction, **kwargs)
+
+    def default_hp_space(self, trial):
+        return default_hp_space_wandb(trial)
+
+
+ALL_HYPERPARAMETER_SEARCH_BACKENDS = {
+    HPSearchBackend(backend.name): backend for backend in [OptunaBackend, RayTuneBackend, SigOptBackend, WandbBackend]
+}
+
+
+def default_hp_search_backend() -> str:
+    available_backends = [backend for backend in ALL_HYPERPARAMETER_SEARCH_BACKENDS.values() if backend.is_available()]
+    if len(available_backends) > 0:
+        name = available_backends[0].name
+        if len(available_backends) > 1:
+            logger.info(
+                f"{len(available_backends)} hyperparameter search backends available. Using {name} as the default."
+            )
+        return name
+    raise RuntimeError(
+        "No hyperparameter search backend available.\n"
+        + "\n".join(
+            f" - To install {backend.name} run {backend.pip_install()}"
+            for backend in ALL_HYPERPARAMETER_SEARCH_BACKENDS.values()
+        )
+    )

src/transformers/integrations.py

@@ -177,15 +177,6 @@ def hp_params(trial):
     raise RuntimeError(f"Unknown type for trial {trial.__class__}")
 
 
-def default_hp_search_backend():
-    if is_optuna_available():
-        return "optuna"
-    elif is_ray_tune_available():
-        return "ray"
-    elif is_sigopt_available():
-        return "sigopt"
-
-
 def run_hp_search_optuna(trainer, n_trials: int, direction: str, **kwargs) -> BestRun:
     import optuna
 

src/transformers/trainer.py

@@ -36,18 +36,9 @@ from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Tuple, Un
 # Integrations must be imported before ML frameworks:
 # isort: off
 from .integrations import (
-    default_hp_search_backend,
     get_reporting_integration_callbacks,
     hp_params,
     is_fairscale_available,
-    is_optuna_available,
-    is_ray_tune_available,
-    is_sigopt_available,
-    is_wandb_available,
-    run_hp_search_optuna,
-    run_hp_search_ray,
-    run_hp_search_sigopt,
-    run_hp_search_wandb,
 )
 
 # isort: on
@@ -66,6 +57,7 @@ from .data.data_collator import DataCollator, DataCollatorWithPadding, default_d
 from .debug_utils import DebugOption, DebugUnderflowOverflow
 from .deepspeed import deepspeed_init, deepspeed_load_checkpoint, is_deepspeed_zero3_enabled
 from .dependency_versions_check import dep_version_check
+from .hyperparameter_search import ALL_HYPERPARAMETER_SEARCH_BACKENDS, default_hp_search_backend
 from .modelcard import TrainingSummary
 from .modeling_utils import PreTrainedModel, load_sharded_checkpoint, unwrap_model
 from .models.auto.modeling_auto import MODEL_FOR_CAUSAL_LM_MAPPING_NAMES, MODEL_MAPPING_NAMES
@@ -114,7 +106,6 @@ from .trainer_utils import (
     TrainerMemoryTracker,
     TrainOutput,
     default_compute_objective,
-    default_hp_space,
     denumpify_detensorize,
     enable_full_determinism,
     find_executable_batch_size,
@@ -2517,41 +2508,20 @@ class Trainer:
         """
         if backend is None:
             backend = default_hp_search_backend()
-            if backend is None:
-                raise RuntimeError(
-                    "At least one of optuna or ray should be installed. "
-                    "To install optuna run `pip install optuna`. "
-                    "To install ray run `pip install ray[tune]`. "
-                    "To install sigopt run `pip install sigopt`."
-                )
         backend = HPSearchBackend(backend)
-        if backend == HPSearchBackend.OPTUNA and not is_optuna_available():
-            raise RuntimeError("You picked the optuna backend, but it is not installed. Use `pip install optuna`.")
-        if backend == HPSearchBackend.RAY and not is_ray_tune_available():
-            raise RuntimeError(
-                "You picked the Ray Tune backend, but it is not installed. Use `pip install 'ray[tune]'`."
-            )
-        if backend == HPSearchBackend.SIGOPT and not is_sigopt_available():
-            raise RuntimeError("You picked the sigopt backend, but it is not installed. Use `pip install sigopt`.")
-        if backend == HPSearchBackend.WANDB and not is_wandb_available():
-            raise RuntimeError("You picked the wandb backend, but it is not installed. Use `pip install wandb`.")
+        backend_obj = ALL_HYPERPARAMETER_SEARCH_BACKENDS[backend]()
+        backend_obj.ensure_available()
         self.hp_search_backend = backend
         if self.model_init is None:
             raise RuntimeError(
                 "To use hyperparameter search, you need to pass your model through a model_init function."
             )
 
-        self.hp_space = default_hp_space[backend] if hp_space is None else hp_space
+        self.hp_space = backend_obj.default_hp_space if hp_space is None else hp_space
         self.hp_name = hp_name
         self.compute_objective = default_compute_objective if compute_objective is None else compute_objective
 
-        backend_dict = {
-            HPSearchBackend.OPTUNA: run_hp_search_optuna,
-            HPSearchBackend.RAY: run_hp_search_ray,
-            HPSearchBackend.SIGOPT: run_hp_search_sigopt,
-            HPSearchBackend.WANDB: run_hp_search_wandb,
-        }
-        best_run = backend_dict[backend](self, n_trials, direction, **kwargs)
+        best_run = backend_obj.run(self, n_trials, direction, **kwargs)
 
         self.hp_search_backend = None
         return best_run

src/transformers/trainer_utils.py

@@ -301,14 +301,6 @@ class HPSearchBackend(ExplicitEnum):
     WANDB = "wandb"
 
 
-default_hp_space = {
-    HPSearchBackend.OPTUNA: default_hp_space_optuna,
-    HPSearchBackend.RAY: default_hp_space_ray,
-    HPSearchBackend.SIGOPT: default_hp_space_sigopt,
-    HPSearchBackend.WANDB: default_hp_space_wandb,
-}
-
-
 def is_main_process(local_rank):
     """
     Whether or not the current process is the local process, based on `xm.get_ordinal()` (for TPUs) first, then on

tests/trainer/test_trainer.py

@@ -42,6 +42,7 @@ from transformers import (
     is_torch_available,
     logging,
 )
+from transformers.hyperparameter_search import ALL_HYPERPARAMETER_SEARCH_BACKENDS
 from transformers.testing_utils import (
     ENDPOINT_STAGING,
     TOKEN,
@@ -72,7 +73,7 @@ from transformers.testing_utils import (
     require_wandb,
     slow,
 )
-from transformers.trainer_utils import PREFIX_CHECKPOINT_DIR
+from transformers.trainer_utils import PREFIX_CHECKPOINT_DIR, HPSearchBackend
 from transformers.training_args import OptimizerNames
 from transformers.utils import (
     SAFE_WEIGHTS_INDEX_NAME,
@@ -2803,3 +2804,11 @@ class TrainerHyperParameterWandbIntegrationTest(unittest.TestCase):
             trainer.hyperparameter_search(
                 direction="minimize", hp_space=hp_space, hp_name=hp_name, backend="wandb", n_trials=4, anonymous="must"
             )
+
+
+class HyperParameterSearchBackendsTest(unittest.TestCase):
+    def test_hyperparameter_search_backends(self):
+        self.assertEqual(
+            list(ALL_HYPERPARAMETER_SEARCH_BACKENDS.keys()),
+            list(HPSearchBackend),
+        )